摘要
本文利用常规观测资料、加密自动站资料、NCEP再分析资料对比分析2017年4月14日("4·14"过程)和2017年5月1—2日("5·1"过程)南疆中部巴州地区强降水过程,探讨春季强降水天气动力学异同。结果表明:春季强降水发生在副热带西风急流活跃,伊朗副热带高压向北伸展,地面冷锋活动,高低空为急流锋区配置背景中。水汽源地位于东经40°的阿拉伯海—里海附近,沿西方路径进入新疆,在有利风场条件下汇合至巴州地区,高低空急流耦合形成次级垂直环流,干冷空气多方向侵入增强春季降水强度。主要差异在于"4·14"过程是副热带西风急流异常北跳、影响系统西风带短波槽、冷空气西方路径,"5·1"过程则是极锋急流与副热带西风急流汇合、深厚长波槽系统、冷空气西北路径;"4·14"过程是典型急流锋区降水伴有对流性降水,强降水发生时形成两支次级环流圈,3股干冷空气从不同方向向中低层气旋性环流附近汇合激发了另一支低层中尺度次级垂直环流圈的建立;"5·1"过程是典型急流冷锋降水,高空干冷空气在垂直方向向下入侵触发和增强冷锋降水,形成了一支完整强大的次级垂直环流圈造成巴州大范围的系统性降水。
Using the conventional observation data,precipitation data of automatic weather stations and NCEP 1°×1°reanalysis data,we comparatively diagnose two heavy rainfall processes happened in the middle South Xinjiang on 14 April 2017(4·14)and 1 to 2 May 2017(5·1),the similarities and differences in meteorological dynamics of two spring heavy rains are discussed.The results indicate that the spring heavy rains occurred in a background of the active subtropical westerly jet,the northward extended Iranian subtropical high,the active ground cold front,and lower-and upper-level jet-front systems.The water vapor was from the Arabian and Caspian sea of around 40°E,which came into Xinjiang followed by west winds,and then converges at the middle South Xinjiang with the favorable wind condition.The upper-level and low-level jets were coupled to form the secondary vertical circulation,and dry and cold air invasion prompted the atmosphere instability and precipitation intensity.The main differences between two processes are:the subtropical westerly jet was abnormally shifting northwards at 500 hPa,resulting in the short-wave trough and the cold air from western at surface in the April rainfall.While the polar front jet and the subtropical westerly jet were joined together at 500 hPa,there existed a long wave trough and cold air from northwest at the surface in the May rainfall.The April rainfall is a typical jet stream front type rain with convection precipitation,during which there were two secondary vertical circulations formed,with the lower one caused by three cold air flows from different directions,triggering the nearby cyclonic circulation at 850 hPa.The May rainfall is a typical jet stream with cold front,in which the downward incursion of upper-level cold air triggered a powerful integrated secondary vertical circulation and enhanced the precipitation.
作者
周雪英
贾健
刘国强
仇会民
杨柳
Zhou Xueying;Jia Jian;Liu Guoqiang;Qiu Huimin;Yang Liu(Bayingolin Meteorological Observatory,Korla 841000;Urumqi Meteorological Observatory,Urumqi 830002)
出处
《气象科技》
2018年第6期1201-1210,共10页
Meteorological Science and Technology
基金
中央级公益性科研院所基本科研业务费(IDM2016001)
中亚大气科学研究基金(CAAS201823)共同资助
关键词
南疆
春季强降水
环流配置
次级垂直环流
干冷空气
South Xinjiang
spring heavy rainfall
circulation background
sub-vertical circulation
dry and cold air
